For all of these the actual type of the argument is int, but for most purposes you can think of the argument type as char. If the value returned is a value of type int, you must perform an explicit or implicit typecast to obtain a char.
Function Declaration |
Description |
Header File |
|---|---|---|
bool isalnum(char); |
Returns true if its argument satisfies either isalpha or isdigit. Otherwise, returns false. |
cctype |
bool isalpha(char); |
Returns true if its argument is an upper- or lowercase letter. It may also return true for other arguments. The details are implementation dependent. Otherwise, returns false. |
cctype |
bool isdigit(char); |
Returns true if its argument is a digit. Otherwise, returns false. |
cctype |
bool ispunct(char); |
Returns true if its argument is a printable character that does not satisfy isalnum and is not whitespace. (These characters are considered punctuation characters.) Otherwise, returns false. |
cctype |
bool isspace(char); |
Returns true if its argument is a whitespace character (such as blank, tab, or new line). Otherwise, returns false. |
cctype |
bool iscntrl(char); |
Returns true if its argument is a control character. Otherwise, returns false. |
cctype |
bool islower(char); |
Returns true if its argument is a lowercase letter. Otherwise, returns false. |
cctype |
bool isupper(char); |
Returns true if its argument is an uppercase letter. Otherwise, returns false. |
cctype |
int tolower(char); |
Returns the lowercase version of its argument. If there is no lowercase version, returns its argument unchanged. |
cctype |
int toupper(char); |
Returns the uppercase version of its argument. If there is no uppercase version, returns its argument unchanged. |
cctype |